Fourteen (14) LDC Test

[mrbulk]

I recently received two more LDCs to test, making for a grand total of fourteen (14) units.

This time, as suggested by some past comments, the decibel meter (a Meterk Digital Sound Level Meter, Range 30-130dB w/Self-Calibrated Decibel Monitoring) was positioned 25 feet downrange and almost in the line of fire (to capture as much of the forward sound output as possible) which was about a third of the way out to the 25-yard silent pellet trap.

The two new LDCs are:

Mystery Moderator 1 (see below), and Mystery Moderator 2 (see below).

There are no costs shown for the two new LDCs because these so-named Mystery Moderators are newly developed units (by certain members wishing to remain anonymous at this time) that may be produced for sale later, although I am not at liberty to discuss this until further notice, and no pricing has yet been provided.

*Mystery Moderator 1 is machined from 6061-T6 aluminum and consists of four parts: two end caps, the body tube and an internal monocore baffle system. Can be completely disassembled for maintenance. Prototype provided for test was bare aluminum, but final product will be anodized matte-black Milspec HA3.

*Mystery Moderator 2 is a sealed unit so I could not see inside, and coated black in either paint or anodizing.

All LDCs were fired through with the same gun, an Avenger .22 w/reg set at 1800psi and hammer spring turned inward 2.75 rotations.

At these settings the JSB .22 18.13-gr diabolos were averaging 853.33 fps to make 29.32 FPE, definitely not backyard friendly without an LDC.

Below are photos of all the LDC units tested, from longest to shortest, and the knife roll I carried them around in during testing (*note - Diana Chaser factory silencer, although shown, was not tested):

Wolf 35mm diameter
Wolf 30mm diameter
Neil Clague 50fpe custom
Mystery Moderator 2
Huma 40mm Standard
Mystery Moderator 1
Geo Long (Hunter)
TKO Slim
STO Falx (std flow)
Rocker1
DonnyFL Sumo
Diana Chaser Factory (not tested)
Geo Short
DonnyFL Tanto
Zero dB 110C

Here are the results by category:

Sorted Low to High by dB:

DonnyFL Sumo:         81.0, 81.5, 81.8 = 81.43 avg
HUMA Standard 40:      82.4, 82.7, 81.9 = 82.33 avg
DonnyFL Tanto:         82.5, 82.4, 82.6 = 82.50 avg
STO Falx Std. Flow:   83.3, 82.3, 82.3 = 82.63 avg
Mystery Moderator 1:   83.3, 83.8, 83.5 = 83.53 avg
Geo Long (Hunter):      84.0, 83.3, 84.0 = 83.77 avg
ZERO dB 110C:         84.2, 83.8, 84.6 = 84.20 avg
Rocker1:            84.6, 84.6, 84.0 = 84.40 avg
Geo Short:            84.6, 84.6, 84.8 = 84.67 avg
Mystery Moderator 2:   84.5, 85.2, 84.8 = 84.83 avg
Neil Clague:         85.4, 85.9, 85.8 = 85.70 avg
Wolf 35mm diameter:   86.3, 86.1, 85.9 = 86.10 avg
TKO Slim:            87.1, 87.3, 87.5 = 87.30 avg
Wolf 30mm diameter:   88.5, 88.3, 88.8 = 88.53 avg
Bare Barrel: 1 shot caused meter overload @104.4dB

Sorted by PRICE ($):

27   Geo Short      
29   Geo Long      
49   Wolf 30mm      
59   Wolf 35mm      
65   Rocker1         
92   TKO Slim      
99   DonnyFL Tanto   
120   Zero DB 110C   
129   STO Falx      
135   Neil Clague      
150   DonnyFL Sumo   
160   Huma 40mm Std
TBD Mystery Mod 1
TBD Mystery Mod 2

Sorted by VOLUME in cubic inches
(calculated from LDC external dimensions):

5.11   Rocker1         
5.25   TKO Slim      
5.68   Zero DB 110C   
5.99   Mystery Moderator 1
6.02   DonnyFL Tanto   
6.06   Geo Short      
7.33   Mystery Moderator 2
7.68   Geo Long      
8.32   Wolf 30mm      
11.25   Wolf 35mm      
12.10   DonnyFL Sumo   
12.70   STO Falx      
12.88   Neil Clague      
14.14   Huma 40mm Std   

Sorted by WEIGHT (oz.):
Geo Short      1.7      
Geo Long      2.3      
TKO Slim      2.9      
Mystery Mod 2   3.0
Rocker1         3.3      
Zero DB 110C   3.5      
DonnyFL Tanto   3.8      
Mystery Mod 1   4.2
Wolf 30mm      4.7      
DonnyFL Sumo   5.9      
Neil Clague      5.9      
STO Falx      6.4      
Wolf 35mm      6.6      
Huma 40mm Std   7.6

It should be noted that this time, by placing the dB meter almost directly in the line of fire, the forward sound throw was more accurately measured and the loudness differences between the various LDCs magnified.

This was exhibited by the bare barrel’s output overloading the meter, where in the prior 12 LDC test the bare barrel output was able to be measured by this same meter with this same gun at the same power setting.

In fact during the prior test, the extreme spread of each LDC’s dB averages was 5.03 dB (88.43 minus 83.40) with a bare barrel maximum reading of 98.83 dB.

In today’s test, the extreme spread was 7.10 dB (88.53 minus 81.43) and the bare barrel output overwhelmed the meter into overload (measuring a maximum of 104.4 dB before it overloaded).

In other words today’s test was the more accurate of the two, in my opinion.

Again both these tests simply provide relative comparisons using equal, specific and fixed parameters for all LDC units, that may hopefully prove useful to some. Different testing of these exact same units using different parameters may result in different conclusions, so YMMV.

Also rest assured that absolutely no science was harmed (or even used) in the completion of this test.

Thanks for reading!

[CraigH]

Good stuff - Thanks!     Everyone should have a roll bag of moderators.   

[Earl]

good test
good information
good sorting
very interesting
Thank you, mrbulk
Bare barrel is 104.4 db at 25' ahead vs 98.8 db at 6' to the side, WOW.
LDC sound reduction is more at 25' ahead than 6' to the side.

[Jshooter71]

Good stuff - Thanks!     Everyone should have a roll bag of moderators.   

+1, Yes, yes!!!

[Hawkeye51]

Charlie  ......   Nice job!

Do you have a feel for equal size and shape moderators having more muted tones with use of felt or other sound deading material?  Does the hair curler, wrapped with scotchbrite or felt inbetween tight washers come close to any of these?

Likewise do you think metal vs carbon fiber makes a significant, or marginal difference? Opinion question, just your thoughts.

[mrbulk]

Charlie  ......   Nice job!

Do you have a feel for equal size and shape moderators having more muted tones with use of felt or other sound deading material?  Does the hair curler, wrapped with scotchbrite or felt inbetween tight washers come close to any of these?

Likewise do you think metal vs carbon fiber makes a significant, or marginal difference? Opinion question, just your thoughts.

Thanks Mike, and on the muted tones aspect I will admit to a highly subjective impression that among the LDCs I could look into/disassemble that featured soft, sound “deadening” material (like felt, ScotchBrite pad, etc.) SEEMED to have a less “snappy” report.

But overall sound reduction by all (and I mean ALL) of these LDCs was dramatic compared to a bare barrel.

So the smaller differences between each unit’s “already-muffled” sound was not as discernible unless you were listening critically for some reason.

It seems safe to say that most any moderator with properly built internals (meaning not just an empty can) will make a night and day difference to the ear when compared to an unmoderated gun.

By properly built I mean using internal baffles, pathways, felt, or other sound-occupying structures that send enough of the air blast on little wild-goose chases by making them spin/move/bury themselves deep into the little nooks, crannies and crevices built into the unit, going anywhere but out the front exit, while allowing the projectile to make an “unmolested exit” out the front. Units built like this would be significantly effective compared to no device at all.

In fact we may be reaching the point where most properly designed and built LDCs are actually “good enough” in achieving their intended purpose, so that now other selection criteria may come into play such as “type” of sound (snappy vs muffled, high pitched tones vs bass tones, etc.), general appearance, ease of maintenance, size, etc., and most importantly, cost.

Lastly, metal vs CF was not a measurable aspect because none of them to my knowledge were made from “real” carbon fiber, just tape wrap. Meaning on those, the underlying tube material would likely have been some kind of plastic or resin due to their generally lighter weight.

I would take a wild guess that the plastic moderators might have a lower damage threshold if fired through significantly high powered airguns, although proving this would involve destructive testing which I cannot do as some of these units were kindly on loan or donated.

[Earl]

This excellent test was done with a .22 caliber at 29.32 foot pounds of energy.
It would be interesting to see the results of a .177 caliber gun at about 15 foot pounds of energy using the same LDCs. 
My Maximus for example shoots 890 fps with 8.44 gr = 14.8 foot pounds of energy
My Maximus has Geo's LDC on it and is very quiet at 14.8 foot pounds of energy.
It is VERY LOUD shooting inside without Geo's LDC on it.

or......
mrbulk can set his Avenger to 15 FPE and tun the same test again.

[mrbulk]

This excellent test was done with a .22 caliber at 29.32 foot pounds of energy.
It would be interesting to see the results of a .177 caliber gun at about 15 foot pounds of energy using the same LDCs. 
My Maximus for example shoots 890 fps with 8.44 gr = 14.8 foot pounds of energy
My Maximus has Geo's LDC on it and is very quiet at 14.8 foot pounds of energy.
It is VERY LOUD shooting inside without Geo's LDC on it.

Earl you may likely be correct, because differing parameters may yield different results.

For example if these same exact LDCs were used for a .177 caliber gun, one differentiating factor could be the size of the pellet pathway through each moderator’s baffle openings. If one path were slightly larger, then perhaps the diameter of the .177 projectile would not sufficiently curtail air movement alongside the escaping pellet, thereby creating a louder perceived shot volume.

Just my wild guess that could be borne out by actual testing, though I have no .177 PCP guns to test with...

[JuryRigger]

Yet another well-constructed test series .
Thank you for the job well done,
Jesse

[Earl]

This excellent test was done with a .22 caliber at 29.32 foot pounds of energy.
It would be interesting to see the results of a .177 caliber gun at about 15 foot pounds of energy using the same LDCs. 
My Maximus for example shoots 890 fps with 8.44 gr = 14.8 foot pounds of energy
My Maximus has Geo's LDC on it and is very quiet at 14.8 foot pounds of energy.
It is VERY LOUD shooting inside without Geo's LDC on it.

Earl you may likely be correct, because differing parameters may yield different results.

For example if these same exact LDCs were used for a .177 caliber gun, one differentiating factor could be the size of the pellet pathway through each moderator’s baffle openings. If one path were slightly larger, then perhaps the diameter of the .177 projectile would not sufficiently curtail air movement alongside the escaping pellet, thereby creating a louder perceived shot volume.

Just my wild guess that could be borne out by actual testing, though I have no .177 PCP guns to test with...

You could set your Avenger to about 15 FPE and run the same test again.

[mrbulk]

You could set your Avenger to about 15 FPE and run the same test again.

Yes Earl you’re right, I could...

In fact I already tested all these moderators Plus one extra (it came on the gun but its threads won’t fit on my Avenger) through a sub-12fpe CO2 Artemis CP2 (Diana Chaser in the U.S.) just before this latest test, but results started becoming inconsistent due to the climate this time of year (too cold).

Maybe when I get another new LDC or three, I’ll try again and this time do it at lower power. It’s pretty time consuming and a bit of work for a lazy old guy like me to walk 25 feet out (and then 25 more feet back) to the sound meter to reset the freeze-highest-reading button after each shot... 

[Earl]

You could set your Avenger to about 15 FPE and run the same test again.

Yes Earl you’re right, I could...

In fact I already tested all these moderators Plus one extra (it came on the gun but its threads won’t fit on my Avenger) through a sub-12fpe CO2 Artemis CP2 (Diana Chaser in the U.S.) just before this latest test, but results started becoming inconsistent due to the climate this time of year (too cold).

Maybe when I get another new LDC or three, I’ll try again and this time do it at lower power. It’s pretty time consuming and a bit of work for a lazy old guy like me to walk 25 feet out (and then 25 more feet back) to the sound meter to reset the freeze-highest-reading button after each shot... 

Testing with the meter at 25 feet is a 2 person job.
You need someone to sit at the sound meter and record the results and reset the sound meter.
It is too difficult for one person to get up and walk to the meter and record it and then walk back and set up and shoot again.

If you could set the sound meter to reset itself after 15 seconds you could read the max db with a scope from the bench.

[subscriber]

The dB reduction over bare barrel is remarkably close.   Thus a very competitive market; where tone, size, weight and cost perhaps matter more.

I trust the pellet trap was not making more noise than the report.  If that were the case (or the mic was too close to the trap), then all the cans would appear to produce the same dB level.

Before someone argues that his muffler is "a whole dB quieter" than the next one; what is a dB?

While sound pressure doubles for every 3 dB increase, the human ear perceives a doubling in sound volume for a 10 dB increase:

From:  www.sounddeadsteel.com/what-is-a-decibel.html#:~:text=An%20increase%20of%203dB%20doubles,times%20more%20intense%20than%201dB.

The human ear's response to sound level is roughly logarithmic (based on powers of 10), and the dB scale reflects that fact. An increase of 3dB doubles the sound intensity but a 10dB increase is required before a sound is perceived to be twice as loud. Therefore a small increase in decibels represents a large increase in intensity. For example - 10dB is 10 times more intense than 1dB, while 20dB is 100 times more intense than 1dB. The sound intensity multiplies by 10 with every 10dB increase.

As a rule of thumb, every ten decibel increase seems about twice as loud. However, this will vary from person to person and also depends on the pitch of a sound. So a 20 dB increase would be 100 times as powerful (10x10) but sound about 4 times as loud (2x2)

In noise reduction terms a 3dB reduction is actually a 50% reduction in the sound power level of the noise. A reduction of 10dB is an SPL reduction of 90%.

Scroll down for sample sound by dB:  https://geoffthegreygeek.com/amplifier-power/

[mrbulk]

The dB reduction over bare barrel is remarkably close.   Thus a very competitive market; where tone, size, weight and cost perhaps matter more.

I trust the pellet trap was not making more noise than the report.  If that were the case (or the mic was too close to the trap), then all the cans would appear to produce the same dB level.

Before someone argues that his muffler is "a whole dB quieter" than the next one; what is a dB?

While sound pressure doubles for every 3 dB increase, the human ear perceives a doubling in sound volume for a 10 dB increase:

From:  www.sounddeadsteel.com/what-is-a-decibel.html#:~:text=An%20increase%20of%203dB%20doubles,times%20more%20intense%20than%201dB.

The human ear's response to sound level is roughly logarithmic (based on powers of 10), and the dB scale reflects that fact. An increase of 3dB doubles the sound intensity but a 10dB increase is required before a sound is perceived to be twice as loud. Therefore a small increase in decibels represents a large increase in intensity. For example - 10dB is 10 times more intense than 1dB, while 20dB is 100 times more intense than 1dB. The sound intensity multiplies by 10 with every 10dB increase.

As a rule of thumb, every ten decibel increase seems about twice as loud. However, this will vary from person to person and also depends on the pitch of a sound. So a 20 dB increase would be 100 times as powerful (10x10) but sound about 4 times as loud (2x2)

In noise reduction terms a 3dB reduction is actually a 50% reduction in the sound power level of the noise. A reduction of 10dB is an SPL reduction of 90%.

Scroll down for sample sound by dB:  https://geoffthegreygeek.com/amplifier-power/

Thanks for the detailed dB breakdown, Sub. You are right about it coming down to other considerations such as looks and cost, and cans that are too “thick” may begin appearing at the bottom of some lower-mounted scope views as I have already experienced.

It’s like having a car when most are still walking. A Yugo (or whatever slowest worst car there is nowadays) is still leagues ahead of walking, yet not that different from a Mercedes or Ferrari, as long as one’s objective is to simply get from points A to B in a reasonably short time (compared to walking).

So all these moderators are in a whole other class of quiet compared to a bare barrel, yet they are all relatively close to one another in sound reduction utility.

In other words, ever more exotic sound muffling designs may reach a point of diminishing returns which is where I believe we are beginning to approach. At least under that particular set of testing circumstances on that particular day.

And yes, I made sure to locate the silent trap (already quite silent due to the pellets striking a soft claylike material) another 50 feet downrange past the sound meter. From that distance there is no audible noise from the trap that I could hear.

[mrbulk]

...

[mrbulk]

Testing with the meter at 25 feet is a 2 person job.
You need someone to sit at the sound meter and record the results and reset the sound meter.
It is too difficult for one person to get up and walk to the meter and record it and then walk back and set up and shoot again.

Earl I heartily agree! Care to volunteer?

[subscriber]

So, looking at the can volume, length and weight, it seems that Mystery Moderator # 1 offers better than ballpark dB reduction, compared to the others.  The next questions would be about tone and price...

[mrbulk]

*UPDATE: the maker of the MM2 has provided more info on the unit, saying the internal core is -

“...3D printed with PETG material for the 2 baffle section and end caps, with aluminum outer shell and a coat of primer plus 2 coats of enamel. The baffles are of a standard cone shape with supports. The PETG material is like the clear soda bottle material. Very strong stuff.”

[subscriber]

*UPDATE: the maker of the MM2 has provided more info on the unit, saying the internal core is -

“...3D printed with PETG material for the 2 baffle section and end caps, with aluminum outer shell and a coat of primer plus 2 coats of enamel. The baffles are of a standard cone shape with supports. The PETG material is like the clear soda bottle material. Very strong stuff.”

Jolly good! What about MM1? 

[mrbulk]

So, looking at the can volume, length and weight, it seems that Mystery Moderator # 1 offers better than ballpark dB reduction, compared to the others.  The next questions would be about tone and price...

You may have hit the nail on the head here. When all attributes are considered, a unit that does most things better in most categories may turn out to be the best choice, as long as it comes down to a palatable price compared with other units.

If I can get more info it will be added to the appropriate test result category/ies.